From 367ec3e4834cbd611401c2c40a23c22c825474f1 Mon Sep 17 00:00:00 2001 From: Yonghong Song Date: Sat, 9 May 2020 10:59:06 -0700 Subject: [PATCH] bpf: Create file bpf iterator To produce a file bpf iterator, the fd must be corresponding to a link_fd assocciated with a trace/iter program. When the pinned file is opened, a seq_file will be generated. Signed-off-by: Yonghong Song Signed-off-by: Alexei Starovoitov Acked-by: Andrii Nakryiko Link: https://lore.kernel.org/bpf/20200509175906.2475893-1-yhs@fb.com --- include/linux/bpf.h | 2 ++ kernel/bpf/bpf_iter.c | 17 ++++++++++++++++- kernel/bpf/inode.c | 5 ++++- 3 files changed, 22 insertions(+), 2 deletions(-) diff --git a/include/linux/bpf.h b/include/linux/bpf.h index 80b1b9d8a638..b06653ab3476 100644 --- a/include/linux/bpf.h +++ b/include/linux/bpf.h @@ -1022,6 +1022,7 @@ static inline void bpf_enable_instrumentation(void) extern const struct file_operations bpf_map_fops; extern const struct file_operations bpf_prog_fops; +extern const struct file_operations bpf_iter_fops; #define BPF_PROG_TYPE(_id, _name, prog_ctx_type, kern_ctx_type) \ extern const struct bpf_prog_ops _name ## _prog_ops; \ @@ -1145,6 +1146,7 @@ void bpf_iter_unreg_target(const char *target); bool bpf_iter_prog_supported(struct bpf_prog *prog); int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog); int bpf_iter_new_fd(struct bpf_link *link); +bool bpf_link_is_iter(struct bpf_link *link); int bpf_percpu_hash_copy(struct bpf_map *map, void *key, void *value); int bpf_percpu_array_copy(struct bpf_map *map, void *key, void *value); diff --git a/kernel/bpf/bpf_iter.c b/kernel/bpf/bpf_iter.c index e7129b57865f..090f09b0eacb 100644 --- a/kernel/bpf/bpf_iter.c +++ b/kernel/bpf/bpf_iter.c @@ -39,6 +39,8 @@ static DEFINE_MUTEX(link_mutex); /* incremented on every opened seq_file */ static atomic64_t session_id; +static int prepare_seq_file(struct file *file, struct bpf_iter_link *link); + /* bpf_seq_read, a customized and simpler version for bpf iterator. * no_llseek is assumed for this file. * The following are differences from seq_read(): @@ -162,6 +164,13 @@ static ssize_t bpf_seq_read(struct file *file, char __user *buf, size_t size, return copied; } +static int iter_open(struct inode *inode, struct file *file) +{ + struct bpf_iter_link *link = inode->i_private; + + return prepare_seq_file(file, link); +} + static int iter_release(struct inode *inode, struct file *file) { struct bpf_iter_priv_data *iter_priv; @@ -183,7 +192,8 @@ static int iter_release(struct inode *inode, struct file *file) return seq_release_private(inode, file); } -static const struct file_operations bpf_iter_fops = { +const struct file_operations bpf_iter_fops = { + .open = iter_open, .llseek = no_llseek, .read = bpf_seq_read, .release = iter_release, @@ -310,6 +320,11 @@ static const struct bpf_link_ops bpf_iter_link_lops = { .update_prog = bpf_iter_link_replace, }; +bool bpf_link_is_iter(struct bpf_link *link) +{ + return link->ops == &bpf_iter_link_lops; +} + int bpf_iter_link_attach(const union bpf_attr *attr, struct bpf_prog *prog) { struct bpf_link_primer link_primer; diff --git a/kernel/bpf/inode.c b/kernel/bpf/inode.c index 95087d9f4ed3..fb878ba3f22f 100644 --- a/kernel/bpf/inode.c +++ b/kernel/bpf/inode.c @@ -358,8 +358,11 @@ static int bpf_mkmap(struct dentry *dentry, umode_t mode, void *arg) static int bpf_mklink(struct dentry *dentry, umode_t mode, void *arg) { + struct bpf_link *link = arg; + return bpf_mkobj_ops(dentry, mode, arg, &bpf_link_iops, - &bpffs_obj_fops); + bpf_link_is_iter(link) ? + &bpf_iter_fops : &bpffs_obj_fops); } static struct dentry *